The present invention relates generally to household appliances, and more particularly to blenders and food processors.
Blenders are household devices often used to blend or mix drinks or liquids. On the other hand, food processors are household devices commonly used to chop, cut, slice, and/or mix various solid foods such as vegetables, fruits, or meats. Different blade designs and rotation speeds are used in a blender or a food processor in order to accomplish the mixing or cutting actions desired.
Conventional household blenders typically have a motor connected to a blade assembly, and the speed of the rotating blade or motor may be varied based on selections made by the user.
For example, U.S. Pat. No. 3,678,288 to Swanke et al. describes a blender having seven speed selection push buttons. The push-buttons drive slider elements that close switches so as to selectively energize various combinations of fields in a drive motor having multiple fields. Field selection provides seven speeds in a high range. Seven speeds in a low range are obtained by applying only half cycles of the AC energizing voltage to the motor when certain combinations of the switches are actuated. Once a speed selection push button is depressed, the motor is energized until an OFF switch is actuated. The device also has a jogger or pulse mode pushbutton that energizes the motor at one speed only as long as the pushbutton is depressed. Pulsing the motor on/off or at high and then low speeds permits the material being blended to fall back to the region of the cutting knives thereby improving the blending or mixing of the material.
U.S. Pat. No. 3,951,351 to Ernster et al. describes a blender having a rotary switch for selecting a high or low range of speeds and five pushbutton switches for selecting a speed within the selected range. The pushbutton switches connect various segments of the motor field winding in the energizing circuit. This device also includes a pulse mode pushbutton that causes energization of the motor only as long as the pushbutton is depressed. The motor may be energized in the pulse mode at any selected speed.
U.S. Pat. No. 3,548,280 to Cockroft describes a blender provided with 10 speed selection switches. A SCR is connected in series with the motor and has a control electrode connected to resistances that are brought into the electrode circuit by actuation of the speed selection switches to control the angle of firing of the SCR and thus the speed of the motor. This device also has a mode selection switch for selecting the manual mode or a cycling or pulse mode in which the motor is alternately energized and deenergized over a plurality of cycles, the number of cycles being set by a potentiometer controlled by a rotatable knob. In a preferred embodiment, the on and off intervals are set during manufacture but two potentiometers may be provided to enable an operator to vary the on and off times.
U.S. Pat. No. 5,347,205 to Piland describes a blender with a microcontroller for controlling energization of the blender drive motor. The speed of the motor is determined by a manual selection of N speed range selection switches, M speed selection switches, and a pulse mode switch.
Typically, the blade attachment in conventional blenders consists of two generally U-shaped blades, a top blade and a bottom blade, joined together at a central point with their respective ends oriented in opposite directions. Because of this blender blade design, conventional blenders usually are not able to successfully chop, slice, or cut solid food because solid food does not flow into the U-shaped blades without adding liquid. Although the solids may make some contact with the blades, typically at least some liquid must be added to the blender in order to successfully liquefy or cut the solid food into very small pieces.
Another drawback with blenders is the number of different operations that must be performed to successfully blend a mixture. Typically, to blend or mix items in a blender, a user will press a sequence of buttons on the blender. For example, to chop ice, a user may hit a slow button, wait a while, hit a faster speed, wait, hit yet a faster speed, etc. The user may have to stop the blending process to dislodge ice or to assure the ice is coming into contact with the blades. This process can be very frustrating, and with conventional blenders may still result in an unsatisfactory chopping or blending of the items in the blender.
In accordance with one aspect of the present invention, a blender is provided that is programmed to accomplish predetermined functions and routines. The routines are preprogrammed into a microcontroller of the blender and include motor commands that are automatically accessed and implemented upon selection of a desired function. For example, the blender may be preprogrammed with a plurality of routines designed for particular food or drink items, such as by taking a particular sequence of motor commands (e.g., direction of rotation, speed, duration or time of rotation, etc.) which are automatically implemented based on the function (e.g., end result) selected by the user.
In an exemplary embodiment of the present invention, a blender includes a blender base, a container, and a blade base having a blade unit mounted thereon. The blender base includes a motor, a microcontroller, a sensor, and a user interface. The microcontroller is in communication with the motor, and user interface, and can include read only memory, nonvolatile memory, and a central processing unit. The programs with preprogrammed motor commands are stored in the read only memory.
The motor is preferably operable to rotate the blade unit in forward and reverse directions, and to oscillate the blade unit as desired. In a preferred embodiment, the motor is a dual wound motor, but other configurations may be used.
The connection between a shaft for the motor and the blade base may be implemented in a number of ways, but preferably is formed by a male to female connection. In accordance with one aspect of the present invention, both the female and male connection pieces are made of metal. This connection permits a close tolerance fit, as well as a low wear connection. To prevent shock to a user, in accordance with another aspect of the present invention, an insulating bushing is used to isolate the outer surface of the male drive from the metal shaft of the motor. Preferably, the insulating bushing is captured within the male drive member, adding stability and limiting shear stresses in the bushing.
The blender base may be utilized with a number of different components, including a jar having an integral collar, a threaded jar, a single serving beverage container, and a food processor. The jars may include a nonstick coating, such as Teflon. One or more sensors may be present on the blender base to detect the presence of and type of container in which the mixing or processing will take place.
In accordance with another aspect of the present invention, a novel blade unit is provided for a blender. The blade unit enables improved food processing and chopping capabilities. The blade unit is mounted on a blade base, and includes a generally U-shaped blade assembly such as is used in contemporary blenders. In addition, the blade unit includes a second blade assembly that extends substantially radially to the driving axis of the blade unit. In an exemplary embodiment of the present invention, a third blade assembly is provided that is also generally U-shaped. In this exemplary embodiment, the first blade assembly is arranged so that its blades extend upward, and the third blade assembly is arranged so that its blades extend downward. The second, radially-extending blade assembly is sandwiched between the first and third blade assemblies.
A detachment mechanism may be provided that permits a user to easily detach the blade unit from its base. In addition, in accordance with another aspect of the present invention, a cap for the jar is configured so that it fits into the blade base and can be used to remove the blade base from the jar.
In accordance with another aspect of the present invention, a sensor is provided that is arranged and configured to determine strain on the motor. For some routines that are executed by the blender base, if the strain exceeds a threshold, then the microcontroller instructs the motor to reverse directions, permitting dislodging of blocking particles.